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IS 15497 (2004, Reaffirmed 2010) : Gaseous Fire 
Extinguishing Systems--IG 01 Extinguishing Systems. ICS 
13.220.10 




Jawaharlal Nehru 
'Step Out From the Old to the New" 



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Satyanarayan Gangaram Pitroda 
Invent a New India Using Knowledge 



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Indian Standard 

GASEOUS FIRE EXTINGUISHING SYSTEMS 
IG 1 EXTINGUISHING SYSTEMS 



1815497:2004 

REAFRRiVIED 



ICS 13.220.10 



© BIS 2004 

BUREAU OF INDIAN STANDARDS 

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG 
NEW DELHI 110002 

September IQQA Price Group 5 



Fire Fighting Sectional Committee, CED 22 



FOREWORD 

This Indian Standard was adopted by the Bureau of Indian Standards, after the draft fmalized by the Fire 
Fighting Sectional Committee had been approved by the Civil Engineering Division Council. 

The objective of this standard is to provide to the users of IG 01 systems with specific requirements for the control 
of fires of Class A or Class B type. It does not cover the design of explosion suppression systems. 

It is important that the fire protection of a building or plant be considered as a whole. IG 01 total flooding 
systems form only a part, though an important part, of the available fire protection facilities. It should not be 
assumed that the installation of an IG 01 total flooding system necessarily removes the need to consider 
supplementary measures, such as the provision of portable fire extinguishers or mobile appliances for first aid or 
emergency use, or measures to deal with special hazards. 

Controlled inert atmospheres are recognized as effective for extinguishing Class A and Class B fires where 
electrical risks are present. Nevertheless, it should not be forgotten, in the planning of comprehensive schemes, 
that there may be hazards for which this technique is not suitable, or that in certain circumstances or situations 
there may be danger in its use requiring special precautions. 



IS 15497 : 2004 



Indian Standard 

GASEOUS FIRE EXTINGUISHING SYSTEMS 
IG 01 EXTINGUISHING SYSTEMS 



1 SCOPE 

1.1 This standard sets out specific requirements 
for the design and installation of total flooding 
fire extinguishing systems employing IG 01 gas 
extinguishant. This standard is applicable to single 
supply as well as distributed supply systems. 

1.2 This standard complements various general 
requirements applicable to all types of gaseous 
fire-extinguishing systems ( Halocarbon as well as 
inert gas systems ) listed in IS 15493. As such, both 
these standards should be read together before 
designing a system. Where requirements in both 
the standards differ, this standard shall take 
precedence. 

1.3 This standard covers systems operating at 
nominal pressures of 16 MPaat 15°C and20MPaat 
15^Conly. 

1.4 Before using IG 01, nature of fire and fire 
spread shall be studied for suitability of 
extinguishment, as high discharge time of 60 s 
may not be suitable for rapid spreading fires. 

2 REFERENCES 

The standards given below contain provisions, 
which through reference in this text, constitute 
provisions of this standard. At the time of 
publication, the editions indicated were valid. All 
standards are subject to revision, and parties to 
agreements based on this standard are encouraged 
to investigate the possibility of applying the most 
recent editions of the standards indicated below: 



IS No. 



7285:1988 



Title 

Specification for seamless steel 
cylinders for permanent and high 
pressure liquefiable gases 
{second revision) 



15493:2004 



Gaseous 
systems 
requirements 



fire 



extinguishing 
General 



3 GENERAL INFORMATION 

3.1 Application 

3.1.1 IG 01 total flooding system is designed to 
develop a controlled atmosphere in an enclosed 



space yielding a reduced oxygen concentration 
that will not sustain combustion. The appropriate 
IG 01 concentration shall also be maintained until 
the temperature within the enclosure has fallen below 
the re-ignition point. 

3.1.2 The minimum TG 01 concentration necessary 
to extinguish a flame and the minimum oxygen 
concentration necessary to support combustion has 
been determined by experiments for several surface- 
type fires particularly those involving liquids and 
gases. For deep-seated tires, longer soaking times 
may be necessary but are difficult to predict. 

3.1.3 It is important that residual oxygen 
concentrations are not only reached and maintained 
for a sufficient period of time to allow effective 
emergency action by trained personnel but also 
maintained for sufficient period of time. This is equally 
important in all classes of fire since a persistent ignition 
source can lead to a recurrence of the initial event 
once the IG 01 has dissipated. 

4 GAS CHARACTERISTICS AND PROPERTIES 

4.1 IGOl is a colourless, odourless and electrically 
non-conductive gas with a density approximately 
1.4 times that of air. 

4.2 IG 01 gas shall comply with the specification as 
shown in Table I. 

4.3 IG 01 system can be used for extinguishing 
fires of all classes within the limits specified 
in IS 15493. 

4.4 IG 01 gas is argon and its specification and 
physical properties are shown in Table 2. 

4.5 Toxicological information for IG 01 gas are shown 
in Table 3. 

Table 1 Specification for IG 01 

{Clause A.2) 



SI No. 
(I) 

i) 

ii) 
iii) 



Specification 

(2) 
Purity 

Moisture 



Requirement 

(3) 
99.9 percent by volume, 

50 ( X ) 10"^ by mass, 
Max 



Suspended matter None visible 
or sediment 



IS 15497 : 2004 



Table 2 Physical Properties of IG 01 

( Clause 4 A ) 



SI No. 


Property 


Value 


(1) 


(2) 


(3) 


i) 


Molecular mass 


39.9 


ii) 


Boiling point at 0.1 MPa 


"185.9°C 


iii) 


Freezing point 


-189.4X 


iv) 


Critical temperature 


-122.3"C 


V) 


Critical pressure 


4.9 MPa 


vi) 


Critical density 


536 kg/m^ 


vii) 


Vapour pressure at 20°C 


15.2 MPa 


viii) 


Specific volume of superheated 
vapour at 0. 1 MPa and 20X 


0.602 



Table 3 Toxicological Information for IG 01 Gas 

{ Clause 4,5) 

SI No. Property Value 

(1) (2) (3) 

i) No observed adverse effect 43 percent 

level (NOAEL) 

ii) Lowest observed adverse 52 percent 

effect level (LOAEL) 

NOTE — These values are the functional equivalents 
of NOAEL and LOAEL values which correspond to 
12 percent minimum oxygen for the no-effect level 
and 10 percent minimum oxygen for the low-effect 
level. 

4.6 Fill Pressure 

The fill pressure of the IG 01 cylinder shall not exceed 
the values provided in Table 4 for systems operating 
at 16 MPa and 20 MPa respectively. 

Table 4 FillPressureoflG 01 Containers 



SI No. 


System 


Property 


(1) 


(2) 


(3) 


i) 


16 MPa storage 
container 


Filling pressure at 15^C 


ii) 


16 MPa storage 
container 


Maximum container 
working pressure at 55°C 


iii) 


20 MPa storage 
container 


Filling pressure at 15°C 


iv) 


20 MPa storage 
container 


Maximum container 
working pressure at 55°C 


NOTE — Fig. 1 should be referred for further data on 
pressure/temperature relationship 



5 SAFETY OF PERSONNEL 

In addition to the provisions specified 
in IS 15493, the following requirements shall also 
apply. 



5.1 Protection of Occupants 

IG 01 total flooding systems shall not be used 
in design concentrations greater than 52 percent 
( corresponds to injected concentrations of 
74 percent ) in normally occupied areas, unless means 
are provided to ensure safe egress of personnel prior 
to the discharge of the inert gas mixture. 

5.2 In areas, where there is a likelihood of 
significant difference between gross and net 
volumes of the enclosure, utmost care shall be 
exercised in proper system design. 

5.3 Though exposure to the concentration levels of 
oxygen ( 10 to 15 percent and 2.5 to 5 percent by 
volume respectively ) is normally considered to 
produce a negligible risk to the personnel, certain 
provisions like personnel training, warning 
signs, pre-discharge alarms, and discharge inhibit 
switch shall be put in place. In addition, adequate 
ventilation facilities shall be available to exhaust the 
trapped gases following extinguishment process. 

5.4 Minimum safety precautions and safety 
limits that are associated with the use of IGOl areas 
shown in the Tables 5 and 6 below. Since a frre can be 
expected to consume oxygen and form decomposition 
products, personnel shall treat any fire situation as 
an emergency and promptly exit the enclosure. 

5.5 Additional provisions as shown in Table 7 
shall apply to account for failure of safeguards 
( see 5.1 to 5.4 ) to prevent accidental exposures to 
the humans present within the enclosure. 

6 ENCLOSURE STRENGTH AND VENTING 
FACILITIES 

6.1 Venting may be provided at levels as high as 
possible in the enclosure. Strength and allowable 
pressures for average enclosures may be in conformity 
with the 6.3. 

6.2 The building requirements for the type of 
enclosure and free venting required can also be 
calculated from the relevant specifications. 

6.3 Free venting facilities shall be provided for the 
enclosure and the equation for the venting area required 
shall be as follows: 

where 

A = free venting area, in m^; 

Q = IG 01 agent discharge rate, in mVmin; and 

P = allowable strength of the enclosure, in kPa. 

Value of P for various construction types is shown 
in Table 8 ( for exceptionally tight enclosures, value 
of /* shall be trebled ). 



IS 15497 : 2004 



260 



240 



220 





200 


D 




en 




D> 




u. 




05 




JQ 




^^ 


180 


LJJ 




01 




D 




c/) 




(/) 




LU 


160 


CL 





140 



120 



160barat15X 
200barat15X 



i00i— I — \ — n — I — \ — ] — ] — I — ! — I — I — ] — p 

-40-30-20-10 10 20 30 40 50 60 70 80 90 100 



TEMPERATURE (X) 
Fig. 1 Temperature/Pressure Graph FOR IG 01 

Table 5 Minimum Safety Precautions for IG 01 

(Clause 5 A) 



SI No. 


IG 01 Design Concentra 
Percent by Volume 


tion 




Requi 


renients 






hihibit Switch 


Egress in 30 s 


Safety Interlock 


Lock-off Valve 








and Time Delay 


Max 






(1) 


(2) 




(3) 


(4) 


(5) 


(6) 


i) 


Below the NOAEL< 43 




Required 


Not required 


Not required 


Not required 


ii) 


Between NOAEL and LOAEL 


Required 


Required 


Required 


Not required 




43 and 52 












iii) 


Above the LOAEL > 52 




Required 









Table 6 Safety Limits for IG 01 

(Clause 5 A) 



SI No. Safety Limit 

(1) (2) 

i) NOAEL 

ii) LOAEL 

'M^ercentage by volume. 



IG 01 Design Concentration'^ 

(3) 
43 
52 



Residual Oxygen Concentration'^ 

(4) 
12 
10 



IS 15497 : 2004 



Table 7 Human Exposure to IG 01 Agent 

( Clause 5,5 ) 



S! No. 


Exposure 




IG 01 Agent Concentration ( Percentage 


-) . 




Up to 43 Between 
43 and 52 




Between 
52 and 62 




More than 62 


(1) 


(2) 




(3) (4) 




(5) 




(6) 


i) 


Oxygen concentration, 
in sea-level equivalent 


percent 


12 Between 
12 and 10 




Between 
10 and 8 




Less than 8 


ii) 


Status space 




Normally Normally 
occupied occupied 




Normally 
occupied 




Normally 
unoccupied 


iii) 


Exposure time 




Not more Not more 
than 5 min than 3 min 




Not more 
than 30 s 




No exposure 
permitted 



Table 8 Allowable Strength of the Enclosure 

( Clause 63 ) 



SI No. 


Construction 


Type 


Typical Structures 


Allowable Load on Enclosure 
kPa 


(1) 


(2) 




(3) 


(4) 


i) 


Light 




Light weight partitions,, glazing 


1.25 


ii) 


Normal 




Brick 


2.50 


iii) 


Vault 




Reinforced concrete 


5.00 



7 EXTINGUISHING AGENT SUPPLY 

7.1 Quantity 

a) The amount of the IG 01 in the system 
shall be at least sufficient for the largest 
single hazard protected or group of 
communicating hazards that are to be 
protected simultaneously. 

b) Where required, the reserve quantity shall 
be as many multiples of the main supply 
as considered necessary. Normaily, 100 
percent standby supply is recommended. 

c) Where uninterrupted protection is 
expected, it is necessary to keep both main 
and standby supplies permanently 
connected to the distribution piping and 
arranged for quick and easy changeover. In 
other cases, it is permissible to keep the 
standby supply within the protected premises 
in accessible locations. 

d) The quantity of the IG 01 required shall 
be further adjusted to compensate for any 
special conditions, such as unclosable 
openings, forced ventilation, the free volume 
of air receivers that may discharge into the 
risk, altitude ( substantially above or below 
sea ievel ) or any other causes for the 
extinguishant loss. 

7.2 Total Flooding Quantity 

a) The amount of IG 1 required to achieve the 



design concentration shall be calculated 
from the following equations and this 
figure shall need further adjustment as 
stated in 7.1(d): 

V 100 



M- 2.303 



^siogjo 



100-C 



where 
M 
C 



V - 

V - 



S == 



b) 



total flooding quantity, kg; 

design concentration, percent by 
volume; 

net volume of the hazard, m^; 

volume of the structural/similar 
permanent objects in the enclosure 
that gas can not permeate, m^; 

AT, + K^ (7), where K^ and K^ are 
constants specific to the agent 
used and T is minimum 
temperature inside enclosure; and 

S^ "= specific volume of superheated 
agentat2PC,mVkg; 

Specific volume constants for the IG 1 gas 
are A^/- 0.799 68 and A^2 = 0.002 93. IGOl is 
a non-liquefied gas at 1 60 bars. It may also 
be noted that this equation provides an 
allowance for the normal leakage from a tight 
enclosure. 

The agent requirement per unit volume of 
protected space can also be calculated by 
using the Table 9 for various levels of 



SS 15497 : 2004 



concentration corresponding to the 
temperature within the protected enclosure. 

NOTE — Quantity of the agent shaU be the highest 
of the values calculated from the provisions 
contained in 7.2(a) and 7.2(b). 

7.3 The actual quantity of IG 01 gas storage 
required and the resultant residual oxygen 
concentration produced shall be determined in the 
following manner, which shall further subject to 
changes for pressure change due to elevation 
(^^e 7.3.3). 

7.3.1 Enclosure Volumes 

The net enclosure volumes are calculated using 
the following equations: 

K) y = y -V 



where 



y.. = maximum net volume of the 

Max 

enclosure, m*^; 

V = gross volume of enclosure, m^; 

V^ == volume of the structural/similar 
permanent objects in the 
enclosure that gas can not 
permeate, m^; 

^Um "^ iTiinimum net volume of enclosure 
considering the maximum 
anticipated volume of the 
occupancy related to the objects, 
in the enclosure, m-\ and 

J/ = volume of the occupancy related 
objects in the enclosure that gas 
can not permeate, for example, 
furniture fittings, etc, \v?. 

7.3.2 IG 01 Parameters 

The required IG 01 gas quantity, number of 
cylinders, actual injected concentration etc, are 
calculated using the following equations: 



a) IG 01 agent quantity ( Theoretical ) 



^th -^MaxX^, 



.(1) 



A/^,^ = theoretical IG 01 quantity, m^; 

^Max "^ rnaximum net volume of the enclosure, 
m^; and 

C| = appropriate injected concentration. 

b) IG 01 containers 

The number of containers required shall 
be as follows after rounding off as 
appropriate : 

A^ =Hi/^c .........(2) 



N = number of containers; 

tV/^,^ = theoretical IG 01 quantity, m''; and 

M^ = quantity of IG 1 agent per container, 
m^. 

Standard containers with standard filling 
pressures should be adopted to facilitate 
logistics. 

c) Actual quantity of IG 01 agent 

The actual quantity of the agent is determined 
as per the equation below: 

M^ - NxM^ ..(3) 

M^ ==" actual quantity of IG 1 storage, m\ 

N = number of containers; and 

M == quantity of IG 1 agent per container, 
m\ 

d) Actual IG 01 injected concentration 

The actual injected concentration of the agent 
based on the actual quantity of the IG 01 agent 



storage is calculated as below: 



-. (4) 

C^j ==^ actual IG 01 injected concentration 

M^ = actual quantity of IG 1 storage, m^; 
and 

^Max ^ maximum net volume of the enclosure, 



e) Lastly, it is required to adjust the number of 
IG 01 agent containers, where necessary, by 
compensating for ambient pressure change 
due to location elevation as per 7.3.3 and 
round off the number as before. The equation 
in such cases will be as follows : 

N^ = iVx atmospheric correction factor, 

N^ "" adjusted number of containers, and 

N = initial number of containers. 

7.3.3 Atmospheric Correction Factors 

It shall be necessary to adjust the actual IG 01 agent 
quantity for altitude effects. Depending upon the 
altitude, atmospheric correction factor shall be applied 
as per the Table 1 0. The adjusted IG 01 agent quantity 
is determined by multiplying the number of IG 01 
containers by the ratio of average ambient enclosure 
pressure to standard sea level pressure. 

8 CONCENTRATION REQUIREMENTS 

8.1 Fire Extinguishing Concentration 

a) The minimum design concentration of the 
IG 01 agent for Class A surface fire 
( including electrical and electronic ) hazards 



IS 15497 : 2004 



Table 9 Total Flooding Quantity (IG 01) 

[Clause 1.2(b)] 



SI No. 


Temp, °C 


Specific 

Vapour 

Volume 

mVkg 




Mass Req 


uirements of IG 01 per Unit Volume of Hazard, kg/Vg,^^,^j,^,^^ 
Design Concentration ( Percentage by Volume ) 
C 




r 














^ 




T 


S 


34 


38 


42 


46 


50 


54 


58 


62 


(1) 


(2) 


(3) 


(4) 


(5) 


(6) 


(7) 


(8) 


(9) 


(10) 


(H) 


i) 


-40 


0.479 


0.522 


0.601 


0.685 


0.775 


0.872 


0.976 


1,091 


1.217 


ii) 


-35 


0.489 3 


0.511 


0.588 


0.671 


0.758 


0.853 


0.956 


1.068 


1.191 


iii) 


- 30 


0.499 6 


0.501 


0.576 


0.657 


0.743 


0.836 


0.936 


1.046 


1.167 


iv) 


-25 


0.509 8 


0.491 


0.565 


0.644 


0,728 


0.819 


0.917 


1.025 


1.143 


V) 


-20 


0.520 1 


0.481 


0.554 


0.631 


0.714 


0.803 


0.899 


1.005 


1.120 


vi) 


- 15 


0.530 4 


0.472 


0.543 


0.619 


0.700 


0.787 


0.882 


0.985 


1.009 


vii) 


- 10 


0.540 6 


0.463 


0.533 


0.607 


0,686 


0.772 


0.865 


0.966 


1.078 


viii) 


-05 


0.550 9 


0.454 


0.523 


0.596 


0.674 


0.758 


0.849 


0.948 


1.058 


■ ix) 





0.561 2 


0.446 


0.513 


0.585 


0.661 


0.744 


0.833 


0.931 


1.038 


X) 


5 


0.571 5 


0.438 


0.504 


0.574 


0.649 


0.731 


0.818 


0,914 


1,020 


xi) 


10 


0.581 7 


0.430 


0.495 


0.564 


0.638 


0,718 


0.804 


0,898 


1.002 


xii) 


15 


0.592 


0.423 


0.486 


0.554 


0.627 


0,705 


0.790 


0,883 


0.984 


xiii) 


20 


0.602 3 


0.416 


0,478 


0.545 


0.616 


0.693 


0.777 


0.868 


0.968 


xiv) 


25 


0.612 6 


0.409 


0.470 


0.536 


0.606 


0.682 


0.764 


0,853 


0.951 


xv) 


30 


0.622 8 


0.402 


0.462 


0.527 


0.596 


0,670 


0.751 


0.839 


0.936 


xvi) 


35 


0.633 1 


0.395 


0.455 


0.518 


0.586 


0,659 


0.739 


0.825 


0.920 


xvii) 


40 


0,643 4 


0,389 


0.448 


0.510 


0.577 


0.649 


0.727 


0.812 


0.906 


xviii) 


45 


0.653 6 


0.383 


0.440 


0.502 


0.568 


0.639 


0.716 


0.799 


0.892 


xix) 


50 


0.663 9 


0.377 


0.434 


0.494 


0.559 


0.629 


0.704 


0.787 


0.878 


xx) 


55 


0.674 2 


0.371 


0.427 


0.487 


0.550 


0.619 


0.694 


0.775 


0.864 


xxi) 


60 


0.684 5 


0.366 


0.421 


0.479 


0.542 


0.610 


0.683 


0.763 


0.851 


xxii) 


65 


0.694 7 


0.360 


0.414 


0.472 


0.534 


0.601 


0.673 


0.752 


0.839 


xxiii) 


70 


0,705 


0.355 


0.408 


0.465 


0.526 


0.592 


0.663 


0.741 


0.827 


xxiv) 


75 


0,715 3 


0.350 


0.403 


0.459 


0.519 


0.584 


0.654 


0.730 


0.815 


xxv) 


80 


0.725 6 


0.345 


0.397 


0.452 


0.511 


0.575 


0.645 


0.720 


0.803 


xxvi) 


85 


0.735 8 


0.340 


0.391 


0.446 


0.504 


0.567 


0.636 


0.710 


0.792 


xxvii) 


90 


0.746 1 


0.335 


0.386 


0.440 


0.497 


0.560 


0.627 


0.700 


0.781 


xxviii) 


95 


0.756 4 


0.331 


0.381 


0.434 


0.491 


0,552 


0,618 


0.691 


0.770 


xxix) 


100 


0.766 6 


0.326 


0.376 


0.428 


0.484 


0.545 


0.610 


0.682 


0.760 



shall be the extinguishing concentration 
29.2 percent and with a loading of 20 percent 
as a safety factor (35 percent ). 

b) The minimum design concentration of the 
IG 1 agent for Class B hazards shall be the 
extinguishing concentration ( determined by 
Cup Burner test ) with a loading of 30 percent 
as a safety factor. 

c) Combustible solids — The minimum injected 
concentration of IG 01 agent for surface 
type Class A risks shall not be less than 
40 percent by volume which yields, on a free 
efflux basis, a residual oxygen concentration 



of 14 percent by volume in the enclosure. 
9 APPLICATION RATE AND DISCHARGE TIME 

9.1 Rate of Application 

The design application rate shall be based on the 
quantity of IG 01 ( M^ [ see 7.3.2 (c) ] for the desired 
concentration ( see 8.1 ) and for the time allotted to 
achieve the design concentration ( see 7.2 ). The 
oxygen concentration, however, shall be within the 
limits as specified in 5.3. 

9.2 Duration of IG 01 Discharge 

a) The discharge time period is defined as the 



IS 15497 : 2004 



Table 10 Atmospheric Correction Factors 

{Clausel 3.3) 



SI No. 


Equiva 


ilent Altitude, m 


Enclosure Pressure, mm Hg 


Atmospheric 


Correction Factor 


i) 




"920 


840 




1.11 


ii) 




-610 


812 




1.07 


iii) 




-300 


787 




1.04 


iv) 







760 




1.00 


V) 




300 


733 




0.96 


vi) 




610 


705 




0.93 


vii) 




920 


678 




0.89 


viii) 




1 220 


650 




0.86 


ix) 




1 520 


622 




0.82 


X) 




1 830 


596 




0.78 


xi) 




2 130 


570 




0.75 


xii) 




2 440 


550 




0.72 


xiii) 




2 740 


528 




0.69 


xiv) 




3 050 


505 




0.66 



time required to discharge from the nozzles 
95 percent of the agent mass at 27°C, necessary 
to achieve the minimum design concentration 
based on a 20 percent safety factor for flame 
extinguishment. 

b) The minimum theoretical injected 
concentration, that is, 34 percent by volume 
shall be achieved within 1 min and the actual 
injected concentration ( that is the above plus 
a suitable safety factor, adjustment for 
container rounding off ) shall be achieved 
within 2 min, 95 percent of the minimum 
design quantity of the agent shall be released 
within 60s. 

c) Flow calculations performed in accordance 
with 12, or in accordance with the listed pre- 
engineered systems, shall be used to 
demonstrate the discharge time requirements 
stated above. 

d) For explosion prevention systems, the 
discharge time for agents shall ensure that 
the minimum inerting design concentration 
is achieved before concentration of flammable 
vapours reach the flammable range. 

e) When an extended discharge is desired to 
maintain the design concentration for the 
specified period of time, additional quantities 
of agent can be applied at a reduced rate. The 
initial discharge shall be completed within 
the limits as specified above. Performance 
of the extended discharge shall be 
demonstrated by test. 

f) Where containers are situated remote from 
the protected enclosure, extended transit time 
will be apparent. Authorities concerned shall 



be consulted before locating the containers 
in such cases. 

9.3 Retention Time 

Following the discharge of the agent into the 
enclosure, at least 80 percent of the design 
concentration ( or inerting concentration as the case 
may be ) shall prevail when measured after 10 min of 
discharge. 

10 STORAGE CONTAINERS 

The IG 01 storage containers shall comply with the 
following in addition to various requirements contained 
in IS 15493. 

a) The containers used in IG 01 systems shall 
be seamless cylinders confirming to IS 7285 
designed, fabricated, inspected, certified and 
stamped in accordance with the requirements 
of Chief Controller of Explosives. 

b) The storage containers shall have reliable 
means of indicating their pressure. 

c) The storage containers shall have reliable 
means of indicating the variation of container 
pressure with temperature. A pressure/ 
temperature chart ( see Fig. 1 ) attached to 
the container is acceptable. 

d) The requirements of authorities having 
jurisdiction for containers may take presence 
over the requirements of this standard, if their 
specifications are more stringent. 

11 DISTRIBUTION SYSTEM 

The IG 01 distribution system shall comply with the 
following in addition to various requirements contained 



IS 15497 : 2004 



in IS 15493. 

11.1 Piping Network 

a) The piping shall withstand the maximum 
expected pressure at the maximum storage 
temperature, as follows: 

1) 1 6 MPa systems — 20 MPa at 55X, and 

2) 20 MPa systems -— 25 MPa at 55°C. 

b) The piping shall withstand the maximum 
developed pressure at 55°C and shall be in 
accordance with IS 15493. 

c) Carbon steel pipes and fittings shall be 
galvanized inside and outside or otherwise 
suitably protected against corrosion. 
Stainless steel pipes and fittings may be used 
without corrosion protection. 

11.2 Piping Fittings 

a) Pipe fittings shall comply with the 
requirements given in IS 15493. 

b) Fittings shall be selected according to the 
wall thickness or schedule number of the pipe 
to which they are intended to be fitted. 

11.3 Pipe Sizing 

Pipe sizing is a complex issue, particularly when too 
small a bore results in excessive pressure losses 
while two large a bore reduces the flow velocity. This 
may also result in excess pressure drops and 
lower flow rates. The sizes can be checked using an 
approved computer flow calculation programme. 

11.4 Nozzle Placement 

a) The type of nozzles selected, their number 
and placement shall be such that the design 
concentration will be established in all parts 
of the protected enclosure and such that the 
discharge will not unduly splash flammable 
liquids or create dust clouds that could 
extend the life, create an explosion, or 
otherwise adversely affect the contents or 
the integrity of the enclosure. 

b) Nozzles shall be selected and located to protect 
an area less than its area of coverage. The 
area of coverage to the type of nozzle shall 
be so listed for the purpose. 

c) Maximum nozzle height above floor level for 
a single row of nozzles is 3 .5 m. Where ceiling 
height ( of the protected enclosure ) exceeds 
3.5 m, an additional row of nozzles shall be 
provided for uniform and faster distribution 
of the agent within the enclosure. 

d) Minimum nozzle height above the floor level 
of the hazard shall be 0.2 m. 



e) In case of enclosures having no false 
ceiling, nozzles can be located on the ceiling 
anywhere within 0.5 to 5 m from the 
walls. In case of enclosures having false 
ceilings, deflector shields shall be used 
with each nozzle and also nozzles shall be 
so located ( with an anticipation of 
dislodgement of false ceiling materials or 
any movable objects in the path of 
discharge ) to prevent any damage thereto. 

f) Nozzles shall be provided in all the 
concealed spaces, floor voids, ceiling voids, 
etc, besides the main area within the 
protected enclosure. 

g) Selecting the number of nozzles in a system 
shall take into account, the shape of the 
enclosure ( Area and volume ), shape of the 
void ( raised floor, suspended ceiling ). 
Installed equipment in the enclosure/void 
( Chimney effect ), allowed pressure at the 
restrictor ( Pipe quality ), obstructions, which 
may affect the distribution of the discharged 
agent and architectural considerations. 

h) In hazards having suspended ceiling, 
consideration shall be given for having 
nozzles installed in the ceiling void 
( simultaneous discharge ) in order to 
equalize the pressure during discharge, thus 
reducing the risk of unnecessary damaging 
ceiling tiles, etc. 

j) In hazards having raised floor ( not gas- 
tight ) consideration shall be given for having 
nozzles installed in the floor void 
( simultaneously discharge ) in order to 
equalize the pressure and obtain 
extinguishing concentration below the 
floor. 

k) In hazards having suspended ceiling, 
nozzles for protecting rooms void shall be 
installed in such a way that the jets from the 
nozzles do not damage the ceiling plated 
excessively during discharge, that is, the 
nozzles to be positioned vertically with the 
discharge holes free of the ceiling tiles and/ 
or Escutcheon plates. For light weight ceiling 
tiles, it may be recommended to securely 
anchor tiles for a minimum of 1,5 m from 
each discharge nozzle. 

m) It is recommended in enclosures/rooms/ 
voids with heights up to 5 m to have a nozzle 
installed per each 30 m^. 

n) The maximum distance between nozzles 
should not exceed 6 ra and the maximum 
distance to wall/partition should not 
exceed 3 m. 



IS 15497 : 2004 



12 HYDRAULICS OF THE SYSTEM 

12.1 An approved hydraulic calculation method 
shall be employed to predict pipe sizes, nozzle 
pressure, agent flow rate, discharge per nozzle and 
the discharge time. 

12.2 The various parameters described 
in 7.3.1, 7.3.2, 9.1 and 9.2 shall be considered to 
determine the following minimum limits of accuracy: 



a) 



b) 



c) 



The weight of agent predicted by flow 
calculation to discharge from the nozzle 
should agree with the total weight of agent 
actually discharged from each nozzle in the 
system within a range of -5 percent to + 10 
percent of actual prediction. 

The discharge time predicted by the flow 
calculation method should agree with the 
actual discharge time from each nozzle in the 
system within a range of ± 5 s. 

The accuracy of the calculated nozzle 
pressures versus actual pressures at each 
nozzle should be such that actual nozzle 
pressures in an installation will not fall outside 
the range required for acceptable nozzle 
performance. 

The nozzle pressure should not fall below the 
minimum or above the maximum nozzle 
pressure required for the nozzle to uniformly 
distribute the agent throughout the volume 
which that nozzle's discharge is to protect. 

13 COMMISSIONING AND ACCEPTANCE 
TESTING 

13.1 Criteria for Acceptance 

The completed IG 01 total flooding system shall 
be commissioned in accordance with clause 9 
of IS 15493 and the system's performance proved by 
at least one of the following methods: 



d) 



a) 



It is not normally recommended to 
conduct full-scale discharge test of IG 1 
total flooding systems. Where the authorities 
concerned insist on full-scale discharge test, 
the tests shall be conducted in accordance 
with 14. 



b) Where a full discharge test using IG- 01 is 
not insisted by the authorities concerned, 



the following procedure shall apply: 

1) Subject the distribution system to a 
hydrostatic pressure test of 1.50 times 
the calculated pipework's maximum 
developed storage pressure at 5 5 °C, then 
purge the system to remove moisture and 
prove free passage. 

2) Subject the protected area to an 
enclosure integrity test in accordance 
with the procedure given in IS 1 5493. 

13.2 Commissioning Certification 

When the system commissioning is completed 
the installation agency shall issue a typical test 
certificate. 

13.3 Where the system fails to comply with various 
provisions as stated above, the fault shall be rectified 
and, if necessary, the system retested. 

14 IG 01 FULL SCALE DISCHARGE TEST 
PROCEDURE 

14.1 This shall be in accordance with IS 15493. 

14.2 Recommissioning 

Restore all systems to a fully operational status. 

14.3 Reporting 

The following shall be reported: 

a) Information identifying the system shall 
include: 

1) installation, designer and contractor; 

2) enclosure identifications; 

3) enclosure temperature prior to discharge; 

4) oxygen and carbon dioxide residual 
concentrations; and 

5) position of sampling points. 

b) Date and time of test. 

c) Discharge time. 

d) Concentration levels at each sampling point 
at 2 min and 1 min from the commencement 
of discharge. 

e) System deficiencies. 

f) Reference to this test method 
(i'^e IS 15493).